Cell surface structure and organization have been implicated in playing important roles in cell-cell interactions. Tumor cell surfaces have alterations in some components which probably leads to major changes in intercellular regulatory mechanisms. Determining why tumors spread from primary and metastasize to distant secondary sites is an important problem in cancer research, and various studies indicate that cell surface properties may determine ability of tumor cells to metastasize. The primary objective of the proposed research is to define what structural and compositional changes in membrane glycolipid components such as neutral glycolipids, gangliosides, ceramide megalosaccharide glycolipids relate to cell growth and tumor spread in several murine metastatic cell lines that have been selected in vivo for enhanced metastases. The display of surface glycoproteins and glycolipids will be studied using radioisotope labelling techniques. Also, the degree of surface exposure of glycosyltransferases and glycosidases will be studied using covalent glycolipid-glass complexes. Finally, we will attempt to modify the metastatic characteristics of tumor cells by inclusion of specific glycolipids into their surface membrane.